Holding Boost Issue
Originally Posted by Jeff_Jeske
Okay boys and girls.....went out and performed this mod tonight.
The restrictor definately allows the turbo to boost higher under 5k RPM. With the boost map set at 80 the turbo would spike to 26PSI.
After 5K RPM the needle still drops down under 20PSI but I was able to achieve and additional 2PSI (from 16PSI to 18PSI) at 7k RPM if I allowed the midrange to run higher boost as well (22PSI).
So if you were looking for something that would give you more boost when drag racing on race gas this would probably be worth 20HP or so across the entire powerband.
The problem for the daily driver is this: BOOST IS INCONSISTANT
The initial spike is sometimes 26 sometimes 24 sometimes 28. The boost curve that follows the spike changes depending upon the size of the spike. Also, partial throttle boosting or lets just say roll-on-racing style driving also causes a very large boost spike. If I hit the throttle at 5k it would spike to 24PSI. Again on race gas this might not be a problem but on my logger I was seeing knock and timing being pulled.
For my aggressive daily driver and road racer the mod was just too dangerous. The boost was unpredictable and next to impossible to tune for. I'm not sure how the alchy folks are tuning for this. I ended up pulling the restrictor and returning the hoses to stock. I prefer to have a nice solid SAFE 20PSI up to 6500 where it then drops down.
At least I know my car will have rock solid consistant boost no matter where or when I put my foot into it.
The choice is yours.
Respectfully,
Jeff Jeske
The restrictor definately allows the turbo to boost higher under 5k RPM. With the boost map set at 80 the turbo would spike to 26PSI.
After 5K RPM the needle still drops down under 20PSI but I was able to achieve and additional 2PSI (from 16PSI to 18PSI) at 7k RPM if I allowed the midrange to run higher boost as well (22PSI).
So if you were looking for something that would give you more boost when drag racing on race gas this would probably be worth 20HP or so across the entire powerband.
The problem for the daily driver is this: BOOST IS INCONSISTANT
The initial spike is sometimes 26 sometimes 24 sometimes 28. The boost curve that follows the spike changes depending upon the size of the spike. Also, partial throttle boosting or lets just say roll-on-racing style driving also causes a very large boost spike. If I hit the throttle at 5k it would spike to 24PSI. Again on race gas this might not be a problem but on my logger I was seeing knock and timing being pulled.
For my aggressive daily driver and road racer the mod was just too dangerous. The boost was unpredictable and next to impossible to tune for. I'm not sure how the alchy folks are tuning for this. I ended up pulling the restrictor and returning the hoses to stock. I prefer to have a nice solid SAFE 20PSI up to 6500 where it then drops down.
At least I know my car will have rock solid consistant boost no matter where or when I put my foot into it.
The choice is yours.
Respectfully,
Jeff Jeske
so basically it's about the stock turbo running out of steam which means 20g9-5 time...
now my question is... will hte xede be able to control boost perfectly to 7500 with a turbo that is able to flow? and i think the answer is yes.
Last edited by trinydex; Mar 7, 2006 at 10:06 PM.
Originally Posted by trinydex
now my question is... will hte xede be able to control boost perfectly to 7500 with a turbo that is able to flow? and i think the answer is yes.
[QUOTE=Evo23IG][QUOTE=Jorge T]I achieved less taper by adjusting the wastegate rod following FP instructions, (eyelet hole 1/2 over pin diameter for more preload).
I'm actually using the stock WGA, I loosened the nut and turned in the eyelet 3 full turns.
Did modify the stock wastegate rod? If so, can you please explain how to do this or post a link?
Originally Posted by Jorge T
I'm actually using the stock WGA, I loosened the nut and turned in the eyelet 3 full turns.
trinydex - Not a problem glad I could help.
EDIT: it is adjustable
Last edited by Jeff_Jeske; Aug 11, 2006 at 02:34 PM.
Originally Posted by Jeff_Jeske
Are you sure your actuator is stock? Mine is not adjustable.
trinydex - Not a problem glad I could help.
trinydex - Not a problem glad I could help.
i have a question for shiv. if it's not a question of holding peak boost, does the factory sollenoid do a perfect and i mean PERFECT job of BUILDING boost, as in are there any boostup advantages to a manual boost controller or an aem type unit?
or can we just run the xede boost duty cycles at the appropriate values of boost and know that it's stayin' shut when it's suppose to? have any tested info on this?
or can we just run the xede boost duty cycles at the appropriate values of boost and know that it's stayin' shut when it's suppose to? have any tested info on this?
I'm not Shiv but prior to cams the XEDE could hold perfect boost levels all the way to red line. After cams its the turbo that has the problem not the BS.
From what I've read if you have a high flow motor the stock turbo is going to run out of wind no matter what you do.
From what I've read if you have a high flow motor the stock turbo is going to run out of wind no matter what you do.
I know this thread has moved beyond what stock turbos taper to, but here is a post I made about a week ago to a Dynoflash customer that was blaming there less than desirable results on boost taper:
Link: https://www.evolutionm.net/forums/sh...d.php?t=188997
Link: https://www.evolutionm.net/forums/sh...d.php?t=188997
Originally Posted by Smogrunner
Ok,
Here are a few links to stock turbo Evos that show boost levels in the range you are talking about and there is nothing wrong with their cars:
1. https://www.evolutionm.net/forums/sh...d.php?t=188930 Taper to 16 psi
2. https://www.evolutionm.net/forums/sh...d.php?t=180886 Taper to 17 psi
3. https://www.evolutionm.net/forums/sh...d.php?t=180889 Taper to 17 psi
4. https://www.evolutionm.net/forums/sh...d.php?t=180883 Taper to 16 and 17.75
5. https://www.evolutionm.net/forums/sh...d.php?t=181032 Taper to high 16 psi
So you know, I just took the first 5 dyno charts I could find off of the only dyno on Evom that regularly logs and posts boost levels. Take it for what it is worth and good luck finding out why you are making less power than you should be...
Here are a few links to stock turbo Evos that show boost levels in the range you are talking about and there is nothing wrong with their cars:
1. https://www.evolutionm.net/forums/sh...d.php?t=188930 Taper to 16 psi
2. https://www.evolutionm.net/forums/sh...d.php?t=180886 Taper to 17 psi
3. https://www.evolutionm.net/forums/sh...d.php?t=180889 Taper to 17 psi
4. https://www.evolutionm.net/forums/sh...d.php?t=180883 Taper to 16 and 17.75
5. https://www.evolutionm.net/forums/sh...d.php?t=181032 Taper to high 16 psi
So you know, I just took the first 5 dyno charts I could find off of the only dyno on Evom that regularly logs and posts boost levels. Take it for what it is worth and good luck finding out why you are making less power than you should be...
Last edited by Smogrunner; Mar 19, 2006 at 11:58 AM.
Originally Posted by trinydex
that wasn't my question tho... i wanna know if an mbc will boost faster than a solenoid controlled evo.
Jeff,
You need to do more tuning on your boost table. I was able to get a boost curve that worked like CLOCKWORK with that same exact pill in the line. If you still have the bleeder in the line near the BCS may be your culprit as well. I tuned mine to 25psi spike falling to 22psi at 7800 for everyday driving....cranked up the initial spike to 27psi for the strip.
what you basically have to do is tune the boost map to get your correct initial spike and gradually increase it at every RPM interval until you get to about 5500-6000 and then have it high enough where essentially the BCS isn't even controlling boost, the wastegate just can't hold anymore than 22psi about about 6000.
never had a problem with inconsistancy. i would not suggest running such high boost levels at the road course...even with meth injection i lowered my boost on the road course. still with a 25psi spike but let it fall to 18-19psi at 7000.....
You need to do more tuning on your boost table. I was able to get a boost curve that worked like CLOCKWORK with that same exact pill in the line. If you still have the bleeder in the line near the BCS may be your culprit as well. I tuned mine to 25psi spike falling to 22psi at 7800 for everyday driving....cranked up the initial spike to 27psi for the strip.
what you basically have to do is tune the boost map to get your correct initial spike and gradually increase it at every RPM interval until you get to about 5500-6000 and then have it high enough where essentially the BCS isn't even controlling boost, the wastegate just can't hold anymore than 22psi about about 6000.
never had a problem with inconsistancy. i would not suggest running such high boost levels at the road course...even with meth injection i lowered my boost on the road course. still with a 25psi spike but let it fall to 18-19psi at 7000.....
I spent three hours on my boost map and still couldn't get consistant mid RPM boost levels. With that restrictor in line, if I hit the throttle at 5k it would spike much higher than it would if I punched it at 3k and worked my way up to 5k. I couldn't tune for that. Maybe with alchy you have a safety zone to play with but on straight pump my timing was all over the place.
If the problem truely is the wastegate opening before it should then an adjustable actuator would fix that problem without having to tweak any map. On my 2G DSM I had the FP adjustable actuator and didn't even need a MBC. I set the WG to my desired PSI and it was rock solid from there on out.
I may just take the plunge and get an actuator. I honestly dont feel comfortable doing back to back to back WOT runs with boost spiking all over the place.
If the problem truely is the wastegate opening before it should then an adjustable actuator would fix that problem without having to tweak any map. On my 2G DSM I had the FP adjustable actuator and didn't even need a MBC. I set the WG to my desired PSI and it was rock solid from there on out.
I may just take the plunge and get an actuator. I honestly dont feel comfortable doing back to back to back WOT runs with boost spiking all over the place.
did you put the pill between the compressor and the T or between the wastegate and the T?
also, 25psi spike and holding 22psi to redline is too high for pump gas anyway. pump gas it needs to be tapering lower and spiking lower.
also, 25psi spike and holding 22psi to redline is too high for pump gas anyway. pump gas it needs to be tapering lower and spiking lower.
do you guys have the newest xede stuff? doesn't the conditionals give you overboost so you don't have too worry about the top as much.. .just have a modest initial spike and the xede will do the rest?